Instrument for truing up cylindrical surfaces.



N0.-729,329. PATENTED MAY 26, 1903.

' LM. GRIFFIN & 0. P. ALLEN.

INSTRUMENT FOR TRUING UP GYLINDRIOAL SURFACES.

APPLICATION FILED AUG. 13, 1902.

H0 MODEL.

| 5 Z a is ITNESSES I INVEgOB S UNITED STATES Patented May 26, 1903.

PATENT OFFICE".

JUDSON M. GRIFFIN AND OLIVER PERRY ALLEN, OF DETROIT, MICHIGAN.

INSTRUMENT FOR TRUING UPCYLINDRICAL SURFACES.

SPECIFICATION forming part Of Letters Patent NO'. 729,329, dated Ma 26, 1903.

Application filed August 13, 1902. Serialllo. 119,497. (No model.) I

To all whom it may concern:

Be it known that we, J UDsoN M. GRIFFIN and OLIVER PERRY ALLEN, citizens of the United States, residing at Detroit, county of Wayne, State of Michigan, have invented a certain new and useful Improvement in Instruments for Truing up Cylindrical Surfaces; and We declare the following tobe a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it pertains to make and use the. same, reference being had to the accompanying drawings, which form a part of this specification.

This invention relates to instruments for truing up cylindrical surfaces, and has for its object an improved implement the special purpose of which is to true up and renew the surface of the commutator-cylinders of dynamos and motors. As is well known, the cylinders of dynamos and motors are subject to the wear and destructive action of an electric current, which soon and frequently injures or destroys the commutator, making it necessary to in some way plane the surface and arrange to keep the surface in a substantially cylindrical form, and the implement which forms the object of this invention is to be usedfor the purpose of producing such new surfaces and keeping the commutator-cylinder always in a substantially cylindrical form.

The implement consists of at least three abrading-blocks, at least one of which is preferably rigidly held,and the remainder of which are adjustable to bring the abrading-faces of all the blocks into the proper arched arrangement to produce a true circle by the use of the implement.

In the drawings, Figure l is a section 1ongitudinal of the handle and across the abrading-blocks. Fig.2 is a cross-section showing a detail of the bar on which the adjustable block is held. Fig. 3 is a perspective showing a detail of the adjustable block and its holder. Fig.4 shows a block entirely insulated from the socket.

A indicates the socket for a handle B. The socket is hollow and has inserted in it a bar 2, which is longitudinally movable along the axis of the socket A. It is held from rotation by being made in polygonal formas, for example, a form that is triangular in crosssectionand held in a polygonal opening in the socket A. One face of the bar 2 is provided with a bearing-surface or, preferably, with a bearing-plate 3, that may or may not 'beprovided with a large number of fine serrations or notches. In the socket A is a seatopening 4, in which is inserted a loose plate 5, and in the side of the socket is pivotally secured a cam-lever or a wedge-lever 6, arranged to bear against the loose plate 5 and to hold the loose plate 5 against the plate 3 on the bar 2. The bar 2 is held from escaping from its position in the socket A by a collar 7, that engages against a shoulder 8 at the upper terminus of the polygonal opening of the end of the socket.

The socket A is branched at its outer end and on each branch carries a recess-seat 9 for the reception of the large end of a prismoidal abrading-block 13, which is held in place by a plate 14 and screw 15. A plate of insulating material 16 is affixed at the outside of the head part ofthe implement at each side thereof by screws 17, that are countersunk so far that their heads do not project to contact anything that the insulating-block 16 may I ed, while the cylinder itself is rapidly rotated.

The abrading-blocks are of any suitable material for the purpose that is to be effected. For ordinary grinding of dynamo-commutators the abrading-blocks'are made from sand, cemented with a suitable cementing material; but for some purposes the blocks should be made of steel, with cut faces like the face of a file, and forother purposes the abrading-blocks should be made of material harder than sand, as emery or corundum.

Insome casesas, for example, where the abrading-block is made of metalit is desirable to insulate the block entirely from the socket by which it is held.

Fig. 4 shows an insulated block in which the socket 41 contains an insulating-lining 42, which entirely insulates the abradingblock 43 from the socket. The insulating material and the block are in this case both pressed forward by screw 44. This character of insulating-block is useful Where the block itself is metallic and provided with filelike serrations on the face of it, a character of block which is very useful for truing up commutators on which there has been formed a very hard ring of material apparently produced by some action of the electrical heat on the copper combined with impurities.

What we claim is- 1. In a tool for trning cylindrical surfaces, the combination of a handle-socket, an arm extending therefrom provided with a seat for an abrading-block, a bar engaging said socket and moving longitudinally with respect to the axis thereof, and provided with a seat for an abrading-block, means for clamping the bar in place in the socket, substantially as described.

2. In a tool for truing up cylindrical surfaces, the combination of a handle-socket, branching arms extending therefrom, each of which is provided with a seat adapted to hold an abrading-block, a sliding bararranged longitudinally in said handle-socket and provided with a seat for an abrading-block, and means for holding the sliding bar, substantially as described.-

3. In a tool for truing cylindrical surfaces, a plurality of arms provided with seats for holding abrading-blocks, means whereby the arms are automatically adjusted to bring the abrading-faces to an arch to correspond to the arch of the cylinder to be trued, and means for holding the parts in adjustment, substantially as described.

In testimony whereof we sign this specifi- 4o 

